Communication using a power line laid in a house (power line communication) has been known. Specifically, communication through a device having a power line communication modem for carrying a signal on the power line and extracting the signal is carried out.
For example, Japanese Patent Laying-Open No. 2003-078457 (Patent Document 1) discloses a power line communication device not requiring a cable dedicated for power supply. In addition, Japanese Patent Laying-Open No. 2006-100939 (Patent Document 2) discloses a technique for realizing power line communication with simplified configuration, with a connection operation being facilitated.    Patent Document 1: Japanese Patent Laying-Open No. 2003-078457    Patent Document 2: Japanese Patent Laying-Open No. 2006-100939